Control for electric circuits



Oct. 17, 1950 Filed July 1o, 1945 W. H. -BRUNS CONTROL FOR ELECTRIC CIRCUITS 2 Sheets-Sheet 1 WMHMWGBM .NVENTOR ATTORNEY Oct. 17, 1950 2,525,767

W. H. BRUNS CONTROL FOR ELECTRIC CIRCUITS Filed July l0, 1945 2 Sheets-Sheet 2 WJLAM HW 63M INVENTOQ ATTORNEY Patented Oct. 17, 1950 2,525,161 CONTROL Fon ELECTRIC cmcUr'rs William Henry Bruns, Lineolndale, N. Y., assignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey' Application July 10, 1945, Serial No. 604,185

11 Claims.

In certain electric circuits it is desirable tok control the circuit in response to some manual operation. In elevator control systems for example, push buttons are providedfor operation by passengers and intending passengers and by car attendants. Mostly these buttons control the stopping of thecar and in some systems they also control the starting of the car. Such buttons which are individual to the landings are known as hall buttons and car buttons, the hall buttons being located at the landings and the car buttons being located in the cars. These are the principal control buttons oi' elevator systems but there are other control buttons and manually operable switches. Most of these are located in the elevator car and are common to the landings such as those for controlling door operation, those for controlling the direction of car travel, those for controlling the startingof the car and in some instances also the stopping of the car, etc. As previously constructed all of these buttons and switches have moving parts and require a certain-amount of pressure to operate them.

One object of the invention is to provide a positive'and reliable control Aof an electric circuit in response to touch.

Another object ofthe invention is to-provide for an electric circuit a manually operable control which has no moving parts.

The invention utilizes a cold cathode gas tube for controlling an electric circuit and involves controlling the operation of the tube in response to persons touching either the envelope of the tube or an operating member connected to thev envelope. The invention will be described as a control for an elevator system, such for example as that disclosed in the co-pending application of William Henry Bruns, Serial No. 696 313, illed September 11. 1946, now Patent 2,468,289, issued April 26, 1949. In carrying out the invention as applied to the registration of a call from a landing according to an arrangement which will be described., a gas fllled electronic tube is provided in a push button xture. 'I'his tube is of a construction having an anode extending close to the top of the glass envelope. The fixture has a face plate of insulating material. The tube is arranged in the fixture so that the top of its envelope is near the face plate. An operating button of conducting material is arranged in the xture face plate adjacent and connected to the top of the envelope. A source of direct current of a certain voltage is connected in the'anodecathode circuit of the tube. A source of alternating current of a certain voltage value is connected from one side of the direct current source to ground. A shield for the tube and button is connected to a point inthe anode-cathode circuit. With this arrangement, when a person touches the button the tube breaks down and remains conductive, registering the call and enabling the touching of the button to be discontinued. When the call is answered a control operation takes place to reduce the potential ditference between the anode and cathode below sustaining value.

In many control operations it is desired to control an electric circuit only so long as a manual operation is continued. In applying the invention to such control arrangements, alternating current voltage is applied to the anode-cathode circuit of the tube. Thus, the tube is conductive only so long as the button or other operating member is touched.

In many cases where electric circuits are manually controlled, it is desirable to indicate whether or not the manual operation has been effected. This is especially true where there is a delayed response to the control operation, as in elevator control systems where when a call is registered from a landing it is not fully answered until a car has made a stop at the landing to take on the passenger who registered the call.

With the electronic push button the tube itself4` may be utilized to provide an illuminated indication that the call is registered, obviating special apparatus for this purpose.

Figure 5 is a simplified wiring diagram for one of the controls of Figures 1, 2 and 3; and

Figure 6 is a simpliiled wiring diagram for an-v y other form of` control embodying the invention.

Referring first to Figures 1, 2 and 3, the hall button fixture therein illustrated provides"both v-` y It may also be used v, for indicating purposes in other manual electronicv an up control U and a down control D. Ina:- lnuch as these controls are of the same construction, only one of them, namely the up control positioned in the upper half of the fixture, will be described, details of this control being illustrated in Figure 4 to which reference should also be made. A cold cathode gas tube I3 is utilized. A tube having a wire anode such as the RCA 1021 or Western Electric 313C has been found satisfactory. An RCA 1C21 tube has been illustrated. This tube has an annular shaped cathode II. The wire anode I2 extends through the central opening of the cathode and perpendlcularly to the cathode to within a short distance o! the top of the glass envelope I3. All but the top I4 of the anode is surrounded by a glass sleeve Il. I3 is a wire loop usually termed a starter electrode. I1 are conductors schematically indicated for connecting these electrodes to the prongs I3 extending from the base 23 of the tube. These g prongs extend into apertures in a socket 2 I. The

socket is pr ded with tabs 22 for making external electrica connections, these tabs being connected to the prongs when the tube is inserted in the socket. Only the tabs connected to circuits are shown. The socket is secured by bolts 23 to a mounting block 24 of insulating material. An aperture 25 is provided in this block through which the prongs I3 and tabs 22 extend. The mounting block is secured by screws 23 to U- shaped brackets 21. These brackets in turn are adjustably secured at their yokes by screws 23 to the outlet box 33, an elongated adjustment aperture 3| being provided in each bracket and an elongated washer 32 common to the mounting screws for each bracket being provided to cover the aperture. The fixture face plate 33, also of insulating material, is secured to brackets 21 by screws 34 preferably .with heads of insulating material.

Immediately in front ci the tube the face plate is provided with ai aperture 43. 'I'he portion 4I of the aperture ashort distancefback from the front of the plateiis enlarged toform a shoulder 42. lExtending to this enlarged portion is a cup shaped me er 43 of light transmitting material such as lucite. The wall 44 of Athis member extends over a portion of the tube envelope. On the base 45 of this member is formed a cylindrical portion 46. This portion fits into aperture 40 and extends to a point .a short distance in front of the face plate. A button 41 of conducting material is positioned in a depression 43 formed centrally thereof in the cylindrical portion 46. A depression 50 is formed in base 43. The button 41 is held in place by screw 5I having its head in depression 50 and extending through an aperture in portion 43 into the button. The paint on the outside of the glass envelope of the tube is removed. An area on the outside of the envelope, preferably near or at the top is covered with conducting material 32 as by painting with colloidal graphite a small spot on the top of the envelope. A helical spring 53, having a snug fit in depression 53 at its end, extends between this spot and a washer 54 beneath the head of the screw 5I to form an electrical connection between the spot and the button. With this arrangement, when the tube is fired,'the light from the tube passes through member 43 to form a ring of light around the button, thus indicating that the call is registered.

The tube is shielded from the outlet box and other grounded elements of the xture to prevent unwanted firing of the tube. This shield desigture 3| in mounting block 24.

nated 33 is in the form of a tube of conducting material which fits over member 43, extending into portion 4I of aperture 4l. The shield extends over a portion oi' the base 23. An angle shaped strap 33 of conducting material has one leg 31 secured as by soldering to shield 55. The other leg 33 is connected to a stud 33 mounted in face plate 33 and extending through an aper- The end of the stud engages a contact spring 32 mounted on the back of the mounting block. Also mounted on the back of the mounting block is a positioning clip 33.

The down control D is symmetrically positioned in the lower half of the fixture. The shield 33 for its electronic tube 33 is connected by a similar strap 31 to stud 33. The connections for the electrodes of the tubes are indicated schematically. 'I'he contact spring 32 is connected by conductor 33 to the tab 22 connected to the anode of the up control tube I3. Another conductor 13 extends from the tab for the anode of up control tube I 3 to the tab for the anode of down control tube 33. A .5 megohm resistor 1| is provided in the connection from spring 32 to the anodes of the control tubes. This resistor is held by clip 33 and is provided to protect the circuits should either shield in assembling contact the grounded outlet box 33. Connection of the anodes to an external circuit is made by a conductor 12 connected to the tab for the anode of the down control tube. The starter electrode of each control tube is connected to the cathode of the tube by a conductor 13. Connection of the cathodes to external circuits is made by conductors 14 and 13 connected to the cathode tabs of the up control tube and down control tube respectively. The face plate 33 ls removed to replace a tube. 'I'his is done by removing screws 34 and lifting the plate. The stud 30. straps 36 and 61, shields 33 and 35, members 43, springs 33, screws 5I and buttons 41 come oil' with the face plate as a unit.

A simplified wiring diagram applicable to one of the controls is illustrated in Figure 5 to which reference may now be had. It will be assumed that this control is up control U. As the control is utilized to register a call, direct current voltage from a source 30 is applied to the anode-- cathode circuit to maintain the tube conducting once fired and thus to enable the finger to be removed. The source 30 is for convenience represented as a battery, the positive side of the source being connected to the anode I2 and the negative side of the source being connected through resistor 3| to the cathode I I. An alternating current source 32 is provided for the firing circuit, one side of this source being connected to ground 33 and the other side being connected to some point in the anode-cathode circuit, indicated as the positive side of the direct current source. The value of the voltage of the direct current source is between sustaining voltage and thev breakdown voltage for the anodecathode oi.' the tube. 'I'he peak voltage value of the alternating current source is high enough to enable even a person wearing gloves to break down the tube but not so high as to result in unwanted operations. For the RCA 1C2i tube, a volt direct current source and a 150 volt peak value alternating current source have been found satisfactory. The ohmic value of resistor 3| for this arrangement is 4000 ohms. This provides a voltage drop when the tube is conducting which may be utilized for various con- `trol operations and for other purposes such as controlling indicating devices.

In operation, upon a person touching the glass envelope of the tube adjacent the anode or the button 41 in the arrangement of Figures l, 2, 3 and `4, alternating current voltage is applied across the gap between the envelope and anode I2-1 the circuit being from one side of the source 82 to the anode and from the other side of the source by way of ground through the persons body to the envelope. This voltage causes sufficient change in the field pattern of the tube to cause the tube to break down between the anode and cathode. With direct current voltage applied to the anode-cathode circuit, the tube remains conductive when the person removes his linger so that the call remains registered. The tube may be extinguished to reset the call by reducing the potential difference a'cross the tube to below sustaining value. In the circuit illustrated, a switch 84 is indicated for this purpose, the switch being opened to extinguish the tube. only short duration so that at the expiration of this period switch 84 is reclosed to permit the registration of another call.

Where it is not desired to maintain the tube conductive when the touch is discontinued, alternating current voltage may be applied to the anode-cathode circuit of the tube. A simplifled wiring diagram for such arrangement is illustrated in Figure 6 where one side of an alternating current source 90 is connected to the anode I2 of the tube and the other side of the source is connected through resistor 8| to the cathode II. The source 82 of alternating current has one side grounded at 83 and the other side connected to the anode of the tube as before.

Where it is advisable to provide a shield from ground, it would be connected in the circuit so as to be on the ungrounded sidey of source 82. Upon a person touching the envelope of the tube or a button or other control element electrically connected to the envelope, alternating current voltage from source B2 is applied across the gap between the envelope and the anode, causing the tube to break down between the anode and the cathode. The tube remains conductive so long as the touch is maintained but is extinguished when the touch is discontinued.

Controls in which alternating current voltage is applied to the anode-cathode circuit of a tube such as in the circuit arrangement of Figure 6 may be used for various purposes in elevator systems. For example such control might serve as the control switch within the elevator car operable to start the car after each stop. A construction similar to that of Figure 4 may be employed for such control but other constructions may be utilized dependent upon the purpose and location of the control.

While the fixture of Figures l, 2 and 3 is for two buttons, single button fixtures may be provided, as for example for the terminal floors and also for intermediate floors in certain types of elevator systems. There may be considerable variation in the construction of the fixture. For example the light transmitting members could be of glass and the face plate moulded around them. Also the light transmitting members could be moulded around the buttons. The light transmitting function could be dispensed with in which event the buttons would be mounted in the face plate. However, the lighting function In resetting calls, this operation is ofl has considerable advantage as it indicates when the control is being exercised. In controls with alternating current voltage applied to the anodecathode circuit, the extinguishing of the light by external means could serve to advise the person touching the control that the touching could be discontinued. Where the lighting function is dispensed with, the paint could be left on tubes such as the RCA 1G21 and W. E. 313C. The buttons and light transmitting members could be flush with the surface of the face plate. The buttons may be coated with non-conducting material which serves as a dielectric this arrangement bing claimed in the co-pending application of William Henry Bruns, Serial No. 31,293. filed June 5, 1948. The spot of conducting material 52 may be positioned at other points on the envelope. It has been found that the most sensitive area on tubes such as the RCA 1G21 and W. E. 313C is on the top near the curved surface leading to the cylindrical portion of the envelope. The spot of conducting material may be of other forms and shapes and may be of material other than graphite such as metal, preferably in leaf form adhered to the envelope.

As regards the circuits for the controls, they too are subjected to considerable variation depending a great deal on the control function exercised. For example,` the resistor 8| may be placed on the anode side of the anode-cathode circuit. A load other than a resistor may be utilized such as the coil of a relay. In certain instances there would be advantage in connecting a condenser across the direct current source in the circuits of Figure 5. The shields may be connected to any point in the anode-cathode circuit. Periodic voltage of some other form may be utilized for the firing circuit.

It is found that the current flow required to break down the tube in response to touch is in the nature of a fraction of a microampere. For this reason it is possible for the tube to be broken down by a person Wearing gloves without utilizing a firing circuit voltage which might prove dangerous to persons manipulating the controls or servicing the system. The impedance of the gloves on say 60 cycles alternating current is fairly high but due to the small amount of current which will break down the tube the impedance drop is relatively low. Thus the voltage which Will overcome this impedance drop and still fire the tube is of a safe value. This is of considerable advantage for elevator controls where passengers and intending passengers often wear gloves, as do car attendants. While the invention has been especially directed to controls for use in elevator systems, it is to be understood that the controls may be used for other purposes. Also such controls are suitable for installations in which explosion proof switches are required.

Therefore as many variations may be made and as many apparently widely different embodiments of the invention can be made without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A control manually operable by the touch of a person comprising; a cold cathode gas tube having a cathode and an anode; a button electrically connected to conductive means contiguous to the outside of the envelope of said tube adjacent said anode and adapted to be touched by ausge? to the envelope of said tube adjacent said anode..

by way of ground through the body of said person?4 and said button, said source of impulses having avoltage value suilicient to cause breakdown of the tube only upon said completion of said last named circuit with said ilrst named source of current connected to said anode-cathode circuit; and an electrostatic shield surrounding said anode and said button and being conductively connected t0 said anode-cathode circuit.

2. A control manually operable by the touch of a person comprising; a cold cathode gas tube having a cathode and an anode; a source of current to which the anode-cathode circuit of the tube is resistively connected, said source having a voltage value above the sustaining voltage of the tube but insulcient of itself to cause breakdown of the tube; a source of periodic current connected on one side to the anode-cathode circuit and on the other side to ground; conducting material on a portion of the outside of the envelope of the tube adjacent .said anode; a button comprising conductive matter electrically connected to said conducting material; a ilring circuit for the tube completed by a person touching said button, said circuit extending from ground through the body of said person and said button to said conducting material, said periodic source of current having a voltage value to cause breakdown of the tube only upon completion of said firing circuit with said first named source of current connected to said anode-cathode circuit; and an electrical shield encircling said tube, button and conducting material, and being conductively connected to the ungrounded side of said source of periodic current.

3. A control comprising; a cold cathode gas tube having an anode and a cathode in a glass envelope, said anode being in the form of a wire ending at a point close to the top of the envelope; conducting means on the outside of the envelope over a certain area adjacent said anode; a button comprising conductive material electrically connected to said conducting means; a source of direct current for the anode-cathode circuit of the tube of a voltage value to maintain the tube conductive once it is broken down but insufficient of itself to cause breakdown of the tube; an impedance in said anode-cathode circuit external of the tube; a source of alternating current having one side grounded and the other side connected to a point in said anode-cathode circuit, said alternating current source being o1' a voltage value to cause breakdown of the tube only upon a person touching said button with said direct current source connected to said anode-cathode circuit and conductive shielding means surrounding said tube, conducting means and button to substantially isolate said tube, conducting means and button from the electrostatic field of said source of alternating current.

4. A control comprising; a cold cathode gas tube having an anode and a. cathode in a glass envelope, said anode being in the form of a wire ending close to the top of the envelope; conducting means on the outer surface of the envelope over a certain area adjacent said anode; a button comprising conductive material electrically connected to said conducting means; a source of direct current for the anode-cathode circuit of the tube of a voltage value to maintain the vtube conductive once it is broken down but insuilicient of itself to cause breakdown of the tube; an impedance in said anode-cathode circuit external of the tube; a shield comprising conductive material surrounding said tube and button, said shield being connected to a point in the anode-cathode circuit of the tube; and a source of alternating Lcurrent having one side grounded and the other side connected to a point in said anode-cathode circuit, said alternating current source being of a voltage value to cause breakdown of the tube only upon a person touching said button with said direct current source connected to said anode-cathode circuit.

5. A control in accordance with claim 4 in which the impedance in said anode-cathode circuit external oi the tube is a resistor; and in which there is provided light transmitting mate rial adjacent said tube and having a surface adjacent said button to which it transmits light from said tube when the latter is conductive.

6. A control comprising; a cold cathode gas tube having an anode and a cathode in a glass envelope, said anode being in the form of a wire extending at its end close to the top of the envelope; conducting means adhered to the outside of the envelope adjacent said end of the anode; a button of conducting material adjacent and connected to said conducting means; a source oi direct current for the anode-cathode circuit of the tube, the voltage of said source being insuiiicient to break down the tube but sufficient to maintain the tube conductive once it is broken down; a resistor connected in series with said source in said anode-cathode circuit; a shield for said tube and button, said shield being conductively connected to a point in the anode-cathode circuit of the tube; and a source of alternating current having one side grounded and the other side connected to a point in said anode-cathode circuit of the tube and having a voltage value to cause suillcient change in the ileld pattern of the tube only upon a person touching said button to cause breakdown of the tube between said anode and cathode with said direct current source connected to said anode-cathode circuit.

7. A control manually operable by the touch of a person comprising; a cold cathode gas tube having a cathode and an anode in a glass envelope, said anode being in the form of a wire extending close to the top oi' the envelope; a button of conducting material connected to the outside of the envelope at the top thereof to be touched by said person to operate the control; a source of direct current for the anode-cathode circuit of the tube of a voltage value to maintain the tube conductive once it is broken down but insuiilcient to cause breakdown oi the tube; resistance in said anode-cathode circuit external of the tube; a source of alternating current; a tiring circuit for said tube extending from said alternating current source to the envelope of said tube adjacent said anode by way of ground through the body of said person, said alternating current source having a voltage value to cause breakdown of the tube upon completion of said firing circuit with said direct current source connected to said anode-cathode circuit; light transmitting material around said tube and having a iace to which it conducts the light of said tube when ignited, said button being embedded in said face; and opaque material surrounding said light transmitting material at said i'ace.

8. A control for manual operation by the touch of a person comprising; a casing having an opening at the front thereof; a face plate of insulating material covering said opening; a cold cathode gas tube in said casing, said tube having a cathode and an anode in a glass envelope; conducting means covering a portion of the outside of the envelope; a button to be touched by said person, said button being on the front of said face plate and comprising conductive material conductively connected to said conducting means; and a shield comprising conductive material surrounding said tube and button.

9. A control for manual operation by the touch of a person comprising; a casing having an opening at the front thereof; a face plate of insulating material covering said opening; a cold cathode gas tube in said casing extending toward said face plate, said tube having a cathode and an anode in a glass envelope; the end of said anode extending close to the envelope; conducting means adhered to the outside of the envelope adjacent said end of said anode; a button to be touched by said person, said button being on the front of said face plate and comprising conductive material conductively connected to said conducting means; and a shield comprising conductive material surrounding said tube and button.

10. A control for manual operation by the touch of a person comprising; a casing having an opening at the front thereof; an opaque face plate of insulating material covering said opening; a cold cathode gas tube in said casing extending toward said face plate, said tube having a cathode and an anode in a glass envelope, the end f said anode extending close to the top of th e envelope; conducting means adhered to the outside oi the envelope at the top thereof; a button on the front of said face plate, said button comprising conductive material conductively connected to said conducting means; means for conducting light from said tube when ignited to the front of said face plate; and an electrostatic shield for said tube and button.

ll. A control for manual operation by the touch of a person comprising; a casing; an opaque cover of insulating material for said casing; a cold cathode gas tube in said casing extending toward said cover, said tube having a cathode and an anode in a glass envelope, said anode being in the form of a wire arranged in a glass sleeve and having a short portion extending out of said sleeve close to the top of the envelope; a cylindrical light transmitting member around said tube and extending through said cover for conducting light from said tube when ignited to the front of said cover; a button comprising conductive material embedded in the center of said end of said cylindrical member; conducting means adhered to the outside oi the envelope at the top thereof and conductively connected to said button; and a shield comprising conductive material surrounding said tube and button, said shield being conductively connected to said anode.

WILLIAM HENRY BRUNS.

REFERENCES CITED The following references are of record in the ille of this patent:

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